Hi', since speex decoder is available now for Palm OS also, I was wondering if I can get some good results for audio books . Currently I'm using 22khz around 20kbps (q -2 ) with ogg. Whatever settings i tried (quality/ bitrate/complexity) - I can't bet speex to sound better ogg per same bitrate. This doesn't make any sence, because speex is supposed to be tuned specially for speach.Moreover, it doesn't obey my commands, for example I wanted to force it to use bitrate of 10 kbps

QUOTE

--bitrate 10 --vbr --comp 6 o:\test\16khz.wav o:\out.spx

Instead, i get bitrate of arund 20, which sound much worse than ogg@20kbps. Why?Can anybody help me?

Moreover, it doesn't obey my commands, for example I wanted to force it to use bitrate of 10 kbps

QUOTE

--bitrate 10 --vbr --comp 6 o:\test\16khz.wav o:\out.spx

Instead, i get bitrate of arund 20, which sound much worse than ogg@20kbps. Why?Can anybody help me?

Are you sure you want to encode at 10 *bits* per seconds. Also, the option is --abr when you want to control the vbr rate, so using --bitrate 10000 will already work much better. Although I personaly recommend --vbr --quality X (with X around 6 maybe?) instead. Using 16 kHz, I *think* Speex should be better than Vorbis when you use bit-rate below ~32 kbps. Above that, Vorbis would probably be better.

I've also given up on Speex, at least temporarily, in favor of Vorbis. I'd been using Speex to encode my audiobook CD's and cassettes ever since Windows binaries of it first appeared, and found its superiority to LAME easily ABX-able (LAME almost always produced an annoying metalic noise at lower bitrates, which Speex did not).

The latest Speex beta, I've found, often produces a similarly annoying noise, which Vorbis does not, and was again easily ABX-able. Ultimately, I found that while Speex is SUPPOSED to be optimized for bitrates up to 44kbps and sampling rates of 8, 16, and 32khz, it only seems to work consistently well at 8khz.

Even for those cases in which I cannot ABX a difference between Speex and Vorbis, I've found that Vorbis rarely produces significantly larger files, so I saw no reason to continue with Speex.

I've wondered if it's the case that most modern audiobook recordings can't be considered "pure speech", even when no background music or sound effects are used.